Recognizer circuit



E. W. PAPPENFUS RECOGNIZER CIRCUIT Filed March 27, 1952 QQQIG@ Nov. 17, 1953 MAXX XKCCCA XVOCCAXX Patented Nov. 17, 1953 RECOGNIZER CIRCUIT Ernest W. Pappenfus, Cedar Rapids, Iowa, as-

signor to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application March 27, 1952, Serial No. 278,933

5 claims. l

This invention relates in general to a recognizer unit for turning on equipment when a predetermined code grouping has been received.

In the transmission of secret messages by radio or wire, it is desirable to start the message recording unit at receiving station in operation only during intervals when a message is being transmitted, rather than allowing it to operate continuously. When no message is being transvision for a charging circuit which is energized c."

upon the reception of prearranged signals but which is de-energized upon reception of a signal which is not within the prearranged triggering code.

Further objects, features and advantages of 4- this invention will become apparent from the following description and claims when read in view of the drawing, in which;

The gure illustrates the reccgnizer circuit according to this invention.

With reference to the drawing, an antenna I0 supplies an input to a receiver Il. The receiver Il might be a superheterodyne receiver adapted to receive a teleprinter message. It is to be realized, of course, that in place of the receiver l l, an

input signal may be received from a wire.

A sequential selector l2 receives the output of the receiver Il and produces a plurality of outputs corresponding to the various characters to be printed. Oftentimes 32 characters comprising the 26 letters of the alphabet, and six other characters such as numbers and punctuation marks are used. The Vsequential selector l2 is well known to those skilled in the art and may be of the type manufactured by the Teletype Corporation.v

Each of the 32 outputs from the sequential selector l2 is connected to a push button switch, designated generally as I3, which comprise a push button l, a pair of contacts l5 and it, and a movable contact Il. The Contact l1 is controlled by the push button It. All of the contacts I6 are connected together and to a common conductor I8.

The conductor I8 is connected to one end of a relay IS which has its opposite end connected to a battery E1 that has its negative side grounded. The relay IS actuates a switch contact 2| which is engageable with a Contact 22 that is connected to the positive side of the battery E1.

Switch contact 2l is connected to a resistor R1 and to the grid 23 of tube V1. A condenser C1 is connected between the grid 23 and ground.

All of the contacts l5 are connected together and to one side of a relay 24. The opposite side of the relay 24 is connected to the positive side of the battery E1. A switch contact 26 is controlled by the relay 2li and is engageable with a contact 2'! which is connected to ground. The switch contact 26 is connected to the grid 23 ci tube V1.

The plate 28 of tube V1 is connected through a relay 29 to B plus. The relay 29 controls a switch 3l which connects a teleprinter 32 to a lead 33 that is connected to the receiver Il. The teleprinter 32 may be of a well known type which produces a printed output on the tape 34.,

A latching relay 36 is pivotally supported ad. jacent the movable contact of switch l3l to ho1d' it in the closed position after the relay 29 has.; been actuated. A relay 31 is connected to a mes. sage end circuit t3 and when energized releases. the latch 38 so that the switch 3l may open., The message end circuit 38 receives a pluralityof inputs from the sequential selector l2 through.

a lead 39.

In operation, an agreed sequence of letters is:

chosen so that upon the reception of the particu-- lar sequence, the teleprinter will be connected to the receiver H through the switch 3l. The sequence is set up by push buttons I4. For example, suppose the top push button I4 in the ngure corresponds to the letter A. If the desired sequence to start the teleprinter is a series of six As, then the first push button la would be pushed to move the contact Il from engagement with contact i5 to engagement with contact it.

As shown in the figure, the only push button which has been pushed is the lower one, designated as MZ, wherein the movable contact ilZ has been moved to engage contact ISZ.` Thus, the only incoming signal which will energize the teleprinter is a series of letters Z. It is to be realized, of course, that the number in the series may be varied by adjustment of the circuitry. When a Z is received, an output pulse is fed from the sequential selector l2 through contact ITZ to the relay i9 which temporarily closes switch 2l,

55 thus connecting the condenser C1 to the positive v"per Vminute rate.

3 terminal of the battery E1, so that it may receive a charging pulse. The amount of charge supplied to the condenser C1 during this short interval when the switch 2| is closed depends on the values of R1 and C1 in a well known manner.

The condenser C1 controls the bias on the grid 23 of tube V1 and this bias may be adjusted so that upon ythe reception ofsix consecutive Zs, the condenser -C1 Vis" charged toapotentialihigh enough so`that the current through vthe tube V1 `will energize the relay 29, thus closing the switch 3l.

To take another example, suppose that instead of a sequence of Zs, that it is desired to close the teleprinter circuit whenavseriesgfrlettersfall consisting of A, B, and Ciara-received. "Jn'tthis case all of the switches I'I are left engaged with the contacts I5 except the rst three'jcorresponding to the letters A, B, and C. The receptionrof six letters, all of which are A, B, or C;-"-willfclose4 the relay 29. However, it is to be noted that if .'anyfletterisi-eceived 1in the sequence which does not correspond to -the.starting-code, the Arelay 2d will 'be energized, thus closing'the contact'26 and v-'disch'argingl the -condenser 7C1 to ground. 'This discharge will occur"completely during the-*inter- 'fval when the'e'ontact 26 is engaged with the con- `tact12l because there'is no resistorin series in the'discharge path.

Once fthe desired starting sequence has been "received, the latch" SG1-will hold the-switch 3l 'closedand the vteleprintere32 Vwill print the infcoming" message. vAt the termination of the messagea stopcsequen'ceof pulses may be transmit- I `t'e'd and 'whenthe desiredseque'n'ce is received 'the fm'essageiendunit'-38will energize 'the relay Si,

thus unlocking the latch 35 to release'switchI 3:'.

-The-me'ss'age `end -tirnaycomprise push buttons |4,'1and-tlieirrelatedcircuitries, similar to that shown in' the starting unit. The .stop sequence should vbe ai'different sequence than 'the start `-.'seduenceUSo-that the :relays 29 Vand-3"! lwill not be simultaneously energized.

Itiis to -berealzedthat the number of letters in sequence whichiactuate the'relay 3| may -be varied,l depending; upon the values .of R1 and C1. vSupposefor example, that-a start: message con- :.sists` of three;groupsrofithreesimilar letters such 4:fas AAABBB and-CCC. 1With amessage `com- ;posed ofv'n-inelettersthe probability of an incoming random'messa'ge Vactuatingthe teleprinter is yonce during a period of one year at aflwords It is to .be realized, .of course, :that in communication links where secrecy. is desired whenno messageis being-.transmitted a `random signal mayxbe'sent so asI to confuse .any 'listen-er who may be attemptingA to break..the code used.

It is seen that this invention provides means for actuating a teleprinter'upon the transmission of a predetermined sequence.

Although this 'invention has been described Awith respect to particular embodiments'thereof,

it is not to be so limited as changes and .modi- 'cations maybe ymade therein which-are within the full intended scope 'of Ithe invention, :as de iin'ed by the. appended-claims.

` I claim:

i 1. -A recognizer'circuit foractuating amechanism" u'p'or'lthe reception of a predetermined `se- `quencepf signals comprising, a signal producing Jmeans, a'plurality of "switchesl connectedto :said signal producing' means fwithieachvswitch c'orre- 4spending-to a particular'output signa-Lapairrof f relays connected in series between oppositelcon- 20 producing means with each tacts of said plurality of switches, a first of said relays controlling a rst movable contact to move it from an open circuit position to a grounded position, a second of said relays connected to a sec- 5 ond movable contact to move it from an open circuit position to a closed position, a voltage source connected to said second movable contact in the closed position, an electron tube, a condenser jiconnectedto" the gridpof said `electron tube, a relO sister connected between the 'second movable contact and said grid, the iirst movable contact connected to said grid, and an actuating means .-connected in the plate circuit of said electron tube so as to be energized on reception of the 515 Y f correctsequence voi"` signals.

Vv`2.`'`Amessage t'start signal for a radio receiver comprising,"afsignal producing means producing :.aplurality of output signals, a plurality of twoway switches receiving outputs from said signal switch corresponding to a particular output` signal, the rst contacts of said pluralityv of vswitches, connected together,

'.the second contacts of saidplurality of switches connected together, a first relay connected to said 254 nrstplurality of contacts, a second relay con- Y nected to said second plurality or" contacts, said :i'lrst and second relays connected together, a volt- .,age source connectedpbetweenthe midpoint of .rsaid rst and second 'relays and ground, second -switchingzmeans controlled .by said first relay,

third switching means -controlled by said second relay, an electron tube, a condenser' connected between vthe grid of said electron tube and ground,

a resistor connected.` betweensaidthird switching lmeans and thegridpofgsaid electron tube, said second switching means connected to the grid of said electron tube, anda third relay connected in the plat-e circuit of-saidelectrontube to actuate a message receive circuit when the correct sequence 40 o1 characters has beenreceived.

3. A control .circuit-comprising, a receiving stantion; a sequentialselectorreceiving the output of -said receiving station and .producing a plurality ofoutputs corresponding tok various input signals, a plurality of switching means connected respectively to various--outputsof said sequential selector.,- rst contactsof-eachzof said plurality of switching means connected together, second contacts of said switching means connected together, a--pair-of relays connected .infseries between the rst and second plurality-.of contacts, a voltage "source connected-between the. midpoint-.of -rst `and -second relays and ground-second switching `means controlled by--the first of .said vrelays and :movable Vfrom 4anmpen circuit positionl `to a fgroundedposition, an-electron tube with its grid connected to said secondv switching means, a third Yswitching means controlled by .said second relay :and `movable Vfrom a Ifirst open circuit positionto .a 4Second-position in engagement 'with said voltage fsource, ar resistor connected-inseries -between said ..\third-switching -means and the control grid `of -..rsaid electron-tube,v a condenser connected be- -f-tween the control gridoi` said electron tube-and ground, :andanV electromagnetic-means connected r .zinstheplate circuitI orsaid -electrontube toactuate the controlled mechanism upon receptionof the 1 desiredl sequence f offsignals.

4. Means for operating a controlled circuit comprising-'receiving means receiving an incoming signal, .al sequential selector receiving-the out- ;1 put of .said receiving means and producing a pluralityof outputs each .corresponding'to a particu- `.-flar.-input signal, al plurality of switchingmeans 75 connected to each of vthe outputs of said sequential selector, first contacts of said plurality of switching means connected together, second plurality contacts of said switching means connected Y together, a pair of relays connected with Vone side together, the other side of said rst relay connected to said rst plurality of contacts oi said yswitching means, the other side of said second relay connected to the second plurality of conl tacts of said switching means, a second switching means ycontrolled by said rst relay to move a switch contact from an open circuit position to a grounded position, a third switching means controlled by said second relay and movable from an open circuit position to a closed circuit position, a voltage source connected to said third switching means in the closed position, a resistor connected to said third switching means, an electron tube with its control grid connected to said yresistor and to said second switching means, a

condenser connected between ground and the grid of said electron tube, and control means connected to the plate circuit of said electron tube and actuated when a pre-determined voltage is applied to the grid of said electron tube.

5. A control circuit comprising, a receiving means receiving an incoming signal, a sequential selector receiving the output of said receiving means and producing a plurality of outputs corresponding to the inputs, a first plurality of switching means connected to each of said outputs from said sequential selector, said first plurality of switching means movable between a pair of contacts, the rst of said plurality of contacts connected together, the second of said plurality of contacts connected together, a pair of relays connected ,in series between the rst and second plurality of contacts, a voltage source connected be tween ground and the midpoint of said pair of relays, a second switching means controlled by said first relay and movable from an open circuit position to a closed circuit position in engagement with ground, a third switching means ,controlledv by said second relay and movable from an open circuit position to a closed circuit position engageable with the positive side of said Voltage source, an electron tube with its control grid connected to said second switching means, a resistor connected in series between said third switching means and the control grid of said electron tube, a condenser connected between the control grid of said electron tube and ground, and actuating means connected in the plate circuit of said electron tube.

ERNEST W. PAPPENFUS.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,287,396 Morse Dec. 10, 1918 1,868,703 Griiiith July 26, 1932 2,094,733 Byrnes Oct. 5, 1937 2,552,174 Holloway May 8, 1951 2,618,699 Dain Nov. 18, 1952. 

